The decision also won't affect people already at the hospital: "Inpatients will continue to be cared for and discharged as soon as they are medically fit. Major trauma cases will be diverted to neighbouring hospitals as will high risk women in labour."

The United Lincolnshire Hospitals NHS Trust has also shut down its systems as a "precautionary measure" because it shares clinical IT systems with NLAG, it said on its website. As a result, it is cancelling all appointments on Tuesday "unless there is a clinical reason not to."

There's currently no indication as to who is behind the Lincolnshire attack — or even if it was deliberately targeted or not.

Here's the full statement from the Trust's website:

MAJOR INCIDENT - APPOINTMENTS CANCELLED

A virus infected our electronic systems on Sunday October 30 and we have taken the decision, following expert advice, to shut down the majority of our systems so we can isolate and destroy it.

Our main priority is patient safety. A major incident has been called and all planned operations, outpatient appointments and diagnostic procedures have been cancelled for today (Monday) and tomorrow (Tuesday). All patients should presume their appointment/procedure has been cancelled unless they are contacted. Those who turn up will be turned away.

Antenatal clinics and chemotherapy will still go ahead.

Inpatients will continue to be cared for and discharged as soon as they are medically fit. Major trauma cases will be diverted to neighbouring hospitals as will high risk women in labour.

While our emergency departments remain open and are accepting ambulances, we would urge people to only visit if they absolutely need to, i.e it is an accident or emergency. If you are unwell and unsure where to go for treatment call 111 for North Lincs or 01472 256256 for North East Lincs.

We are reviewing the situation on an hourly basis. Our clinicians will continue to see, treat and operate on those patients who would be at significant clinical risk should their treatment be delayed.

Further updates will be posted on the Trust website and social media channels.We would like to apologise to all patients who are affected.